This article examines the evolution of militarism in US foreign policy in the West Asia region from September 11, 2001 to 2025. The main question is how militarism, as a dominant framework, has shaped Washington’s foreign policy strategies and instruments through different presidential terms and what consequences it has had for the regional security order. Using the theory of structural realism and concepts such as hegemony, balance of power, and imperial overextension, this study examines four presidential terms (Bush, Obama, Trump, Biden) and the beginning of Trump’s second term using a historical-comparative analysis and process tracing method. The findings show that after September 11, aggressive militarism reached its peak and led to extensive interventions in Afghanistan and Iraq. Since the Obama era, this militarism has gradually shifted from direct intervention and occupation to a “hybrid power” based on proxy wars, strategic sanctions, arms sales, and covert operations, but it has remained the hard core of foreign policy. At the same time, competition with China and Russia has led to a redistribution of military resources and a relative reduction in the priority of West Asia. The article concludes that despite tactical achievements such as the temporary elimination of some terrorist leaders and the relative containment of Iran, militarism has failed to achieve its long-term strategic goals of creating lasting stability, consolidating American hegemony, and fully containing Tehran’s regional influence, and has led to the erosion of the United States’ global power and credibility by fueling instability, arms races, and humanitarian crises.